1. Field of the Invention
The present invention relates to a transmission control system that controls the operation of a selection actuator for moving a shift arm of a transmission in a selecting direction.
2. Description of the Related Art
As a transmission mounted in a vehicle, there has been known, for example, an automatic/manual transmission (AMT) that includes actuators, such as motors, to perform a selecting operation and a shifting operation of a manual transmission (MT) that transmits motive power between an input shaft and an output shaft of a vehicle when a driver manually carries out the selecting and shifting operations.
The present inventors have proposed a control system for performing a shifting operation of an automatic/manual transmission by adopting response specifying control in the previous application, namely, Japanese Patent Laid-Open Publication No. 2004-211717. In the control system, a coupling sleeve, for example, that integrally rotates with an input shaft is moved into contact with a synchronized gear through the intermediary of a synchronizer ring, and the coupling sleeve and the synchronized gear are rotationally synchronized to perform the shifting operation.
In this case, the response specifying control is conducted by determining a manipulated variable for driving actuators so as to converge the value of a switching function to zero. The switching function is defined by a linear function based on the difference between a target position and an actual position of a coupling sleeve. A computing coefficient of the linear function is set to lower disturbance suppressing capability level so as to produce a compliance property, which is resiliency of, for example, rubber, thereby damping contact impacts when the coupling sleeve comes into contact with the synchronizer ring.
There has been also proposed a control system that has achieved improved stability of sliding mode control by limiting a model parameter identification range when identifying a model parameter in a model equation of a control object that changes due to deterioration with age or disturbance, thus restraining the occurrence of drift of a model parameter (refer to, for example, Japanese Patent Laid-Open Publication No. 2003-15703).
A conventional automatic/manual transmission control system calculates a target value Psl_cmd of a position in the selecting direction Psl and a target value Psc_cmd of a position in the shifting direction Psc of the shift arm involved in the selecting operation and the shifting operation in response to a speed change command to conduct positioning control by a selection controller that controls the operation of a selection actuator such that Psl agrees with Psl_cmd. Further, the positioning control is carried out by a shift controller that controls the operation of a shifting actuator such that Psc agrees with Psc_cmd.
FIG. 31A is a control block diagram showing a construction example of the selection controller. A selection controller 200 handles a selecting device 201 of an automatic/manual transmission according to a model represented by the following expression (1).Psl(k+1)=a1—sl·Psl(k)+a2—sl·Psl(k−1)+b1—sl·Vsl(k)+b2—sl·Vsl(k−1)  (1)
where Psl(k): Position in the selecting direction of a selecting device 201 in a k-th control cycle; a1_sl, a2_sl, b1_sl, and b2_sl: Model parameters; and Vsl(k): Control input supplied to an actuator of the selecting device in the k-th control cycle.
The selection controller 200 determines a control value Vsl of a voltage to be applied to an actuator (not shown) of the selecting device 201 such that the position Psl of the selecting device 201 in the selecting direction agrees with its target value Psl_cmd. The selection controller 200 includes a subtracter 202 for calculating a difference E_sl between a selected position Psl and a target position Psl_cmd, a switching function value calculator 203 for calculating a value of a switching function σ_sl, an adaptation law input calculator 204 for calculating an adaptation law input Uadp_sl, a reaching law input calculator 205 for calculating a reaching law input Urch_sl, an equivalent control input calculator 206 for calculating an equivalent control input Ueq_sl, and an adder 207 for calculating a control value Vsl of an applied voltage by adding the adaptation law input Uadp_sl, the reaching law input Urch_sl, and the equivalent control input Ueq_sl.
The switching function calculator 203 calculates the switching function value σ_sl according to the following equation (3) from the difference E_sl(k) calculated by the subtracter 202 according to the following equation (2).E—sl(k)=Psl(k)−Psl—cmd(k−1)  (2)σ—sl(k)=E—sl(k)+VPOLE—sl·E—sl(k−1)  (3)
where σ_sl(k): Switching function value in a k-th control cycle; and POLE_sl: Switching function setting parameter (−1<POLE_sl<0).
The equivalent control input calculator 206 calculates the equivalent control input Ueq_sl according to the following equation (4). The reaching law input calculator 205 calculates the reaching law input Urch_sl according to the following equation (5). The adaptation law input calculator 204 calculates the adaptation law input Uadp_sl according to the following equation (6).
                                                        Ueq              —                        ⁢                          sl              ⁡                              (                k                )                                              =                                    1                              b                ⁢                                                                  ⁢                                  1                  —                                ⁢                sl                                      ⁢                          {                                                                    (                                          1                      -                                                                        VPOLE                          —                                                ⁢                        sl                                            -                                              a                        ⁢                                                                                                  ⁢                                                  1                          —                                                ⁢                        sl                                                              )                                    ·                                      Psl                    ⁡                                          (                      k                      )                                                                      +                                                      (                                                                                            VPOLE                          —                                                ⁢                        sl                                            -                                              a                        ⁢                                                                                                  ⁢                                                  2                          —                                                ⁢                        sl                                                              )                                    ·                                      Psl                    ⁡                                          (                                              k                        -                        1                                            )                                                                      -                                  b                  ⁢                                                                          ⁢                                      2                    —                                    ⁢                                      sl                    ·                                          Vsl                      ⁡                                              (                                                  k                          -                          1                                                )                                                                                            +                                                      Psl                    —                                    ⁢                                      cmd                    ⁡                                          (                      k                      )                                                                      +                                                                            (                                                                                                    VPOLE                            —                                                    ⁢                          sl                                                -                        1                                            )                                        ·                                          Psl                      —                                                        ⁢                                      cmd                    ⁡                                          (                                              k                        -                        1                                            )                                                                      -                                                      VPOLE                    —                                    ⁢                                      sl                    ·                                          Psl                      —                                                        ⁢                                      cmd                    ⁡                                          (                                              k                        -                        2                                            )                                                                                  }                                      ⁢                                                      (        4        )            
where Ueq_sl(k): Equivalent control input in a k-th control cycle.
                                          Urch            —                    ⁢                      sl            ⁡                          (              k              )                                      =                                            -                                                                    Krch                    —                                    ⁢                  sl                                                  b                  ⁢                                                                          ⁢                                      1                    —                                    ⁢                  sl                                                      ·                          σ              —                                ⁢                      sl            ⁡                          (              k              )                                                          (        5        )            
where Urch_sl(k): Reaching law input in a k-th control cycle; and Krch_sl: Feedback gain.
                                          Uadp            —                    ⁢                      sl            ⁡                          (              k              )                                      =                              -                                                            Kadp                  —                                ⁢                sl                                            b                ⁢                                                                  ⁢                                  1                  —                                ⁢                sl                                              ·                                    ∑                              i                =                0                            k                        ⁢                                          σ                ⁢                _sl                            ⁢                              (                i                )                                                                        (        6        )            
where Uadp_sl(k): Adaptation law input in a k-th control cycle; and Kadp_sl: Feedback gain.
The adder 207 calculates a control value Vsl(k) of a voltage to be applied to an actuator of the selecting device 201 according to the following equation (7).Vsl(k)=Ueq—sl(k)+Urch—sl(k)+Uadp—sl(k)  (7)
Referring to FIG. 31B, in the selecting device 201, a shift arm 211 is selectively positioned at points Psl_12, Psl_34, Psl_56, and Psl_r at which the shift arm 211 engages shift pieces 210a, 210b, 210c, and 210d for different speeds, which are attached to the shift arm. There are cases where the shift pieces 210 disposed are displaced due to backlashes or individual variations of the device or due to shocks, vibrations or the like. FIG. 31B shows a case where the shift piece 210b, for example, has been dislocated downward.
In such a state wherein the shift piece 210 has been dislocated, if a selecting operation is performed to make a shift from 5th/6th gear select position Psl_56 to 1st/2nd gear select position Psl_12, then the shift arm 211 comes in contact with a chamfered portion of the shift piece 210b, interfering with each other. At this time, the selection controller 200 is required to cancel the interference between the shift arm 211 and the shift piece 210b by canceling a chamfer direction component Fsc′ of a force Fsc generated by the positioning control of the shift actuator by a chamber direction component Fsl′ of a force Fsl generated by a selection actuator to move the shift arm 211 downward in the figure.
In the conventional selection controller 200 constructed as illustrated in FIG. 31A, disturbance compensation based on the adaptation law input Uadp_sl has been used to cope with the aforementioned problem occurring in the selecting operation. However, the disturbance compensation based on the adaptation law input Uadp_sl is calculated using an integral value of the switching function σ_sl(k) according to the above equation (6), so that if a large disturbance by Fsc is applied, then it takes much time until a compensation therefor is reflected in the adaptation law input Uadp_sl(k). This has been inconveniently leading to deteriorated performance of following a target value Psl_cmd of a position in the selecting direction of the shift arm 211.
Furthermore, in a conventional automatic/manual transmission control system, the response specifying control has been used to control the selection actuator by the selection controller to ensure maximized suppression of the occurrence of overshoot in the positioning in the selecting direction, thereby shortening the time required for the selecting operation.
However, there are cases where the dynamic characteristic of a selecting device of a transmission to be controlled deviates from a standard dynamic characteristic assumed beforehand because of changes in the torque characteristic of a shift actuator (motor or the like) attributable mainly to variations in the friction characteristic of the automatic/manual transmission, fluctuation in a supply voltage, or individual variations in mechanical components.
FIGS. 32A and 32B illustrate displacements of the shift arm during the selecting operation. The axis of ordinates indicates target position Psl_cmd and actual position Psl of the shift arm in the selecting direction, while the axis of abscissas provides a common time axis t. FIG. 32A shows the displacement of the shift arm when the characteristic of the selecting device remains within the standard characteristic range, while FIG. 32B shows the displacement of the shift arm when the dynamic characteristic of the selecting device is out of the standard characteristic range.
Referring to FIG. 32A, when the target position Psl_cmd in the selecting direction is changed from Psl_cmd60 to Psl_cmd61 at t61 to begin the selecting operation, the shift arm moves to Psl_cmd61 without vibrations or overshooting. Then, the selecting operation is completed at t62 when the conditions that determine the completion of the selecting operation, namely, (1) ΔPsl (=Psl−Psl_cmd)<D_Psl (a determination value of a rate of change) and (2)|Psl−Psl_cmd61 |<E_Pslf (a determination value of difference) are satisfied.
Referring to FIG. 32B, when the selecting operation is begun at t61, the shift arm overshoots, exceeding Psl_cmd61 and a vibration takes place. The vibration leads to a longer time for the conditions (1) and (2) for determining that the selecting operation is completed to be satisfied at t63 and the selecting operation is completed, as compared with the case illustrated in FIG. 32A. This inconveniently delays the start of the shifting operation that follows the selecting operation, resulting in prolonged time required for speed change processing.